KR102060571B1 - Composite electrolyte, secondary battery, battery pack and vehicle - Google Patents

Abstract

Embodiment of this invention relates to a composite electrolyte, a secondary battery, a battery pack, and a vehicle.
The present invention provides a composite electrolyte capable of realizing a secondary battery having excellent rate performance and low temperature performance, a secondary battery having the composite electrolyte, a battery pack having the secondary battery, and a vehicle having the battery pack.
According to one embodiment, a composite electrolyte is provided. This composite electrolyte has a lithium ion conductivity of 1 × 10 ⁻¹⁰ S / cm or more at 25 ° C., and includes inorganic compound particles containing a solvent, an organic electrolyte, and a binder. The average particle diameter of an inorganic compound particle is 0.1 micrometer or more and less than 5 micrometers, and the weight ratio of the solvent with respect to the total weight of an inorganic compound particle and a solvent is 0.1 weight% or more and less than 8 weight%.

Description

Composite electrolytes, secondary batteries, battery packs and vehicles {COMPOSITE ELECTROLYTE, SECONDARY BATTERY, BATTERY PACK AND VEHICLE}

Embodiment of this invention relates to a composite electrolyte, a secondary battery, a battery pack, and a vehicle.

In recent years, research and development of secondary batteries, such as a lithium ion secondary battery and a nonaqueous electrolyte secondary battery, are progressing vigorously as a high energy density battery. The secondary battery is expected as a power source for a vehicle power source such as a hybrid vehicle or an electric vehicle, or for an uninterruptible power source for a mobile phone base station. In particular, as a vehicle-mounted battery, an all-solid-type lithium ion secondary battery has been actively studied, and its high safety has attracted attention.

Since the all-solid-state lithium ion secondary battery uses a solid electrolyte as compared to a lithium ion secondary battery using a nonaqueous electrolyte, there is no fear of ignition. However, the current situation is that the high capacity all-solid-state lithium ion secondary battery has not been put to practical use yet. One reason for this is that the interface resistance between the solid electrolyte and the active material is high. Since both are solid, when heat is applied, it is relatively easy to bond the solid electrolyte and the active material. However, since the active material expands and contracts with insertion and desorption of lithium, the active material may peel off from the solid electrolyte when repeated charging and discharging is performed, so that a good cycle may not be performed.

Therefore, it is said that the influence of expansion and contraction of the active material is alleviated, and formation of a good interface between the solid electrolyte and the active material is required.

The problem to be solved by the present invention is a composite electrolyte capable of realizing a secondary battery having excellent rate performance and low temperature performance, a secondary battery having the composite electrolyte, a battery pack having the secondary battery, and a vehicle having the battery pack. To provide.

According to the first embodiment, a composite electrolyte is provided. This composite electrolyte has a lithium ion conductivity of 1 × 10 ⁻¹⁰ S / cm or more at 25 ° C., and includes inorganic compound particles containing a solvent, an organic electrolyte, and a binder. The average particle diameter of an inorganic compound particle is 0.1 micrometer or more and less than 5 micrometers, and the weight ratio of the solvent with respect to the total weight of an inorganic compound particle and a solvent is 0.1 weight% or more and less than 8 weight%.

According to the second embodiment, a secondary battery is provided. This secondary battery contains the composite electrolyte which concerns on 1st Embodiment.

According to the third embodiment, a battery pack is provided. This battery pack is provided with the secondary battery which concerns on 2nd Embodiment.

According to the fourth embodiment, a vehicle is provided. This vehicle is provided with the battery pack which concerns on 3rd embodiment.

According to the said structure, the composite electrolyte which can implement | achieve the secondary battery excellent in rate performance and low temperature performance, the secondary battery provided with this composite electrolyte, the battery pack provided with this secondary battery, and the vehicle provided with this battery pack can be provided. have.

1 is a cross-sectional view schematically showing an example of a secondary battery according to the first embodiment.
2 is an enlarged cross-sectional view of part A of FIG. 1;
3 is a partially cutaway perspective view schematically showing another example of the secondary battery according to the first embodiment.
4 is an enlarged cross-sectional view of part B of FIG. 3;
5 is a sectional views schematically showing another example of the secondary battery according to the first embodiment.
6 is a perspective view schematically showing an example of the battery pack according to the first embodiment.
7 is an exploded perspective view schematically showing an example of a battery pack according to a second embodiment.
FIG. 8 is a block diagram showing an example of an electric circuit of the battery pack shown in FIG. 7.
9 is a sectional views schematically showing an example of a vehicle according to a fourth embodiment.
10 is a diagram schematically showing another example of a vehicle according to the fourth embodiment.
The graph which shows the result of the thermogravimetry which concerns on an Example and a comparative example.
The graph which shows the result of the differential scanning calorimetry which concerns on an Example and a comparative example.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment is described, referring drawings. In addition, the same code | symbol is attached | subjected to common structure through embodiment, and the overlapping description is abbreviate | omitted. In addition, each figure is a schematic diagram for promoting description and understanding of embodiment, and although the shape, dimension, ratio, etc. are different from an actual apparatus, they refer to the following description and a well-known technique, and design changes suitably. Can be.

(1st embodiment)

According to the first embodiment, a composite electrolyte is provided. This composite electrolyte has a lithium ion conductivity of 1 × 10 ⁻¹⁰ S / cm or more at 25 ° C., and includes inorganic compound particles containing a solvent, an organic electrolyte, and a binder. The average particle diameter of an inorganic compound particle is 0.1 micrometer or more and less than 5 micrometers, and the weight ratio of the solvent with respect to the total weight of an inorganic compound particle and a solvent is 0.1 weight% or more and less than 8 weight%.

The composite electrolyte is an electrolyte including inorganic compound particles having lithium ion conductivity, an organic electrolyte, and a binder. The composite electrolyte may contain the inorganic compound particle which has lithium ion conductivity, an organic electrolyte, and a binder. When the mixture of an organic electrolyte and a binder is heated, for example, a gel electrolyte can be obtained. The composite electrolyte may include a gel composition containing an organic electrolyte and a binder. When this gel and the inorganic compound particle | grains which have lithium ion conductivity are combined, lithium ion conductivity improves compared with the case where only some inorganic compound particle exists or only gel exists. This is considered to be because the movement of lithium ions between the inorganic compound particles is promoted by the gel containing the organic electrolyte.

When the lithium ion conductivity of the inorganic compound particles is high, the mobility of lithium ions in the particles is also easy, so that the lithium ion conductivity as the composite electrolyte is higher. As for the inorganic compound particle which the composite electrolyte which concerns on this embodiment contains, lithium ion conductivity in 25 degreeC is 1 * 10 <^-10> S / cm or more.

Lithium ions present in the inorganic compound particles can move freely in accordance with an external electric field. For example, when the inorganic compound particles and the gel are disposed as a solid electrolyte between the positive electrode and the negative electrode, the potential difference between the positive electrode and the negative electrode is received, and polarization occurs at the contact interface between the inorganic compound particles and the gel. This polarization causes lithium ions to collect on the surface of the inorganic compound particles, whereby a portion with a high concentration of lithium ions is formed in the particles. As a result, it is thought that the movement of lithium ions from one particle to another is promoted.

However, when the average particle diameter of an inorganic compound particle is too large, since the space | gap between particle | grains tends to increase, it takes time to diffuse lithium ion in a composite electrolyte, and rate performance and low temperature performance fall. Therefore, the average particle diameter of the inorganic compound particle which concerns on embodiment is 0.1 micrometer or more and less than 5 micrometers. When the average particle diameter of the inorganic compound particles is less than 5 µm, the diffusion rate of lithium ions can be increased. The average particle diameter of preferable inorganic compound particle is 0.1 micrometer or more and less than 2 micrometers.

When gelling an organic electrolyte with a binder, if a large amount of solvent is present inside or on the surface of the inorganic compound particles, gelation becomes difficult or the time until gelation becomes a long time.

As described above, in order to gel the organic electrolyte, for example, an electrolyte solution containing a polymer material is heated, but the electrolyte solution deteriorates when the time to gelation is long. Degradation of electrolyte solution is decomposition of electrolyte salt, for example.

In addition, during this gelation, the positive electrode and the negative electrode may generate side reactions with the electrolyte solution. Side reactions are mainly the production of organics on the electrode surface. This organic substance is a factor which increases the resistance of an electrode. Therefore, since the side reaction can be suppressed as the gelation time is shorter, the electrode resistance is lowered and the degradation of the rate performance and the low temperature performance can be suppressed.

In the composite electrolyte according to the present embodiment, in order to easily gel the organic electrolyte and the binder, the weight ratio of the solvent to the total weight of the inorganic compound particles and the solvent containing the inorganic compound particles is 0.1% by weight to 8% by weight. It is in the range of less than%. The measuring method of the amount of solvent in an inorganic compound particle is mentioned later.

The solvent contained in the inorganic compound particles includes a solvent present inside the inorganic compound particles and a solvent present on the particle surface. The solvent which exists inside the inorganic compound particle exists, for example in the state which the molecule | numerator of an inorganic compound and the molecule | numerator of a solvent are chemically bonded. The solvent which exists on the particle surface exists, for example in the state chemically bonded with the molecule | numerator of the inorganic compound on the particle surface, or in the state physically adsorb | sucked to the particle surface.

According to the above structure, since gelation time can be shortened and electrode resistance can be reduced, and conductivity of lithium ion can be improved, the composite electrolyte excellent in rate performance and low temperature performance can be obtained.

The composite electrolyte according to the present embodiment will be described in detail.

Inorganic compound particles have a lithium ion conductivity of 1 × 10 ⁻¹⁰ S / cm or more at 25 ° C. It is preferable that the lithium ion conductivity in 25 degreeC to an inorganic compound particle is 1x10 <^-6> S / cm or more. When the lithium ion conductivity at 25 ° C. of the inorganic compound particles is 1 × 10 ⁻⁶ S / cm or more, the lithium ion concentration in the vicinity of the particle surface tends to be high, resulting in higher rate performance and lower temperature performance. The upper limit of lithium ion conductivity is 1x10 <^-2> S / cm according to an example. It is preferable that lithium ion conductivity exists in the range of 1 * 10 <^-5> S / cm-1 * 10 <^-2> S / cm.

The inorganic compound particles is, for example, an inorganic compound having a Li ₂ SeP ₂ S ₅ based glass ceramics, a perovskite structure of sulfide _{(e.g., Li 0. 5 La 0.} 5 TiO 3), LiSICON structure Inorganic compound having a compound, LATP (Li _{1 + x} Al _x Ti _{2 -x} (PO ₄ ) ₃ ) (0.1≤x≤0.4) having a NASICON skeleton, and Li _{3 . 6} Si _{0 . 6} PO _4, includes at least one selected from the group consisting of the inorganic compound having the _{LIPON (Li 2. 9 PO 3} . 3 N 0 .46) and the garnet-like structure of the amorphous phase. The inorganic compound used as an inorganic compound particle may be one type, or may be two or more types. Inorganic compound particles may contain a mixture of plural kinds of inorganic compounds.

If the inorganic compound particles contain elemental sulfur, it is not preferable because the sulfur component is dissolved in the organic electrolyte described later. It is preferable that an inorganic compound particle does not contain a sulfur element.

Preferred inorganic compound particles are oxides such as LATP having a NASICON skeleton, amorphous LIPON, garnet type LLZ (Li ₇ La ₃ Zr ₂ O ₁₂ ), and the like.

It is preferable that an inorganic compound particle is an inorganic compound which has a garnet-type structure among these. An inorganic compound having a garnet-type structure is preferable because of its high Li ion conductivity and reduction resistance and its wide electrochemical window. Examples of the inorganic compound having a garnet-type structure include Li _{5 + x} A _y La _{3 - y} M ₂ O ₁₂ (A is at least one selected from the group consisting of Ca, Sr and Ba, and M is Nb and Ta). At least one selected from the group consisting of: Li ₃ M _2-x Zr ₂ O ₁₂ (M is at least one selected from the group consisting of Ta and Nb), Li _{7 -3x} Al _x La ₃ Zr ₃ O ₁₂ , and Li ₇ La ₃ Zr ₂ O ₁₂ . In the above, x is 0 <x <0.8, for example, Preferably 0 <x <0.5. y is 0 <= y <2, for example. The inorganic compound which has a garnet-type structure may contain 1 type of these compounds, and may mix and contain 2 or more types of these compounds. Among these, Li _6.25 Al _0.25 La ₃ Zr ₃ O ₁₂ and Li ₇ La ₃ Zr ₂ O ₁₂ have high ion conductivity and are electrochemically stable, and thus have excellent discharge performance and cycle life performance. Moreover, these compounds have the advantage that they are chemically stable with respect to the organic electrolyte mentioned later, even if it becomes microparticles | fine-particles.

The average particle diameter of an inorganic compound particle exists in the range of 0.1 micrometer or more and less than 5 micrometers, Preferably it is in the range of 0.1 micrometer or more and 2 micrometers or less.

The average particle diameter of an inorganic compound particle can be measured by a scanning electron microscope (SEM).

Although the kind of solvent which an inorganic compound particle contains is not specifically limited, For example, polar solvents, such as water, nonpolar organic solvents, such as ethanol, isopropanol, ethylene glycol, and acetone, and polar organic solvents, such as N-methylpyrrolidone, At least one selected from the group consisting of. The solvent contained in the inorganic compound particles is preferably an organic solvent. If the solvent contained in the inorganic compound particles is an organic solvent, the gelation time is less likely to be long, and the electrolyte solution is less likely to deteriorate. The inorganic compound particle may contain only one type of solvent and may contain two or more types of solvents.

The weight ratio of the solvent contained in the inorganic compound particles to the total weight of the inorganic compound particles and the solvent contained in the inorganic compound particles is 0.1% by weight or more and less than 8% by weight. Although it is preferable that this ratio is low, it is difficult to make it 0 weight% because lithium ion contained in inorganic compound particle | grains couple | bonds with water in air on the particle surface. It is preferable that they are 0.2 weight% or more and 5 weight% or less, and it is more preferable that they are 0.1 weight% or more and 2 weight% or less. In this case, the gelation time can be further shortened, and further, excellent rate performance and low temperature performance can be achieved.

The quantity of the solvent which an inorganic compound particle contains can be adjusted as follows, for example.

When dry grinding is employed as the grinding method when the inorganic compound particles are obtained by grinding, the amount of the solvent contained in the inorganic compound particles can be reduced as compared with the case where wet grinding is employed. When wet grinding using a bead mill or the like is employed, there is an advantage that the yield is high, but the amount of the solvent contained in the inorganic compound particles tends to be too large.

Even when wet grinding is employed, the weight ratio of the solvent contained in the inorganic compound particles to the total weight of the solvent contained in the inorganic compound particles and the inorganic compound particles is adjusted by firing the inorganic compound particles so as not to sinter after grinding. It can be made into 0.1 weight% or more and less than 8 weight%. Firing to such an extent that the inorganic compound particles are not sintered is performed at a temperature within the range of 300 ° C to 600 ° C, for example, over 12 hours.

When the inorganic compound particles are sintered, the average particle diameter of the inorganic compound particles increases. In this case, since the space | gap between these particles increases and the ionic conductivity of a composite electrolyte falls, it is unpreferable. In addition, if the average particle diameter of the inorganic compound particles is too large, it is difficult to make the composite electrolyte sufficiently thin when providing the composite electrolyte between the stationary electrodes. As a result, it is not preferable because the distance between the stationary electrodes is increased and the diffusion resistance of lithium ions is increased.

In the case where dry pulverization is employed, the above ratio can be achieved without firing to such an extent that inorganic compound particles are not sintered.

In addition, even when wet grinding is employed, when a solvent having a large molecular size is used as the solvent to be used for grinding, little solvent is introduced into the inorganic compound particles. Therefore, the said ratio can be achieved without baking to the extent that an inorganic compound particle is not sintered.

The weighing method of the solvent contained in an inorganic compound particle is demonstrated.

First, an electrode part is taken out from the battery pack mentioned later, and a part of composite electrolyte formed on the positive electrode surface or the negative electrode surface is scraped off. Inorganic compound particles are obtained by washing and drying the organic electrolyte using a solvent such as diethyl carbonate. Thermogravimetry (TG) is performed to specify the amount of solvent contained in the obtained inorganic compound particles.

When measuring, it heats up on conditions of 10 degree-C / min from room temperature to 900 degreeC, and measures a weight loss. In addition, differential scanning calorimetry (DSC) is also performed at the same time, so that not only the weight of the solvent present on the surface of the inorganic compound particles but also the temperature when the solvent introduced into the inorganic compound particles, that is, the crystals, are decomposed I can tell.

For example, the solvent adsorbed on the particle surface is decomposed within the range of 80 ° C to 150 ° C, the solvent introduced into the crystal within the range of 400 ° C to 500 ° C, and the binder is decomposed within the range of 150 ° C to 250 ° C. In each temperature range, weight loss by TG is observed and endothermic behavior is observed by DSC. From the total value of the reduced weights, the weight of the solvent contained in the inorganic compound particles can be measured by subtracting the weight of the binder.

The weight ratio of the inorganic compound particles to the weight of the composite electrolyte and the solvent contained in the inorganic compound particles is, for example, in the range of 80% by weight to 99% by weight. This ratio becomes like this. Preferably it exists in the range of 90 weight%-98 weight%. When the weight ratio of the inorganic compound particles to the weight of the composite electrolyte and the weight ratio of the solvent contained in the inorganic compound particles are within this range, the effect of suppressing the decomposition of the lithium salt contained in the organic electrolyte is exerted.

The composite electrolyte may contain other particles having a lithium ion conductivity of less than 1 × 10 ⁻¹⁰ S / cm. The other particles having a lithium ion conductivity of less than 1 × 10 ⁻¹⁰ S / cm are preferably at least one selected from the group consisting of aluminum oxide, zirconium oxide, silicon oxide and magnesium oxide, for example in view of high reducibility and low cost. Do. The same effect is also obtained when the other particles are metal oxides such as titanium oxide, niobium oxide, tantalum oxide, hafnium oxide, yttrium oxide, gallium oxide and germanium oxide, and lanthanoid oxides such as lanthanum oxide. Another particle | grain can be made 1 type (s) or 2 or more types chosen from the said compound.

The organic electrolyte contains an organic solvent and an electrolyte salt. The organic electrolyte includes at least one organic solvent selected from propylene carbonate, ethylene carbonate, diethyl carbonate and methyl ethyl carbonate, for example, exhibiting ion conductivity. When these organic solvents are used, there is an advantage that the above-mentioned inorganic compound is hard to melt and can exist stably.

Electrolyte salts include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), bisodium hexafluoride (LiAsF ₆ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ) , A lithium salt such as bistrifluoromethylsulfonylimide lithium [LiN (CF ₃ SO ₂ ) ₂ ], or a mixture thereof. The organic electrolyte may contain other electrolyte salts.

The weight ratio of the organic electrolyte to the weight of the composite electrolyte is, for example, in the range of 0.1% by mass to 20% by mass, and preferably in the range of 1% by mass to 10% by mass. When the weight ratio of the organic electrolyte to the weight of the composite electrolyte is within this range, a lithium ion conduction path that is liable to conduct lithium ions on the surface of the inorganic compound is formed, and a good interface between the composite electrolyte as the solid electrolyte and the active material can be formed. Thus, the effect of improving the high temperature durability and cycle life of the battery is obtained.

The composite electrolyte includes a binder. The composite electrolyte may further contain other additives.

A binder is a high molecular body gelatinized with organic solvents, such as carbonates, for example. Examples of the binder include polyacrylonitrile (PAN), polyethylene oxide (PEO), polyvinylidene fluoride (PVdF), and polymethyl methacrylate. The said binder may be used individually by 1 type, and may mix and use multiple types.

The weight ratio of the binder to the weight of the composite electrolyte is, for example, in the range of 0.1% by weight to 10% by weight, preferably in the range of 0.5% by weight to 5% by weight. If the weight ratio of the binder to the weight of the composite electrolyte is excessively low, the viscosity of the gelled organic electrolyte is insufficient, so that the inorganic compound particles cannot be maintained, and the mechanical strength of the composite electrolyte is lowered or from the electrode. The composite electrolyte tends to peel off. When this ratio is excessively high, it tends to inhibit the movement of lithium ions and increase the diffusion resistance of the ions.

The ionic conductivity of the composite electrolyte is, for example, in the range of 0.1 mS / cm to 20 mS / cm, and preferably in the range of 0.5 mS / cm to 10 mS / cm. The organic electrolyte contained in the composite electrolyte covers at least a part of the solid electrolyte and is gelated appropriately, whereby the ionic conductivity can be achieved. High ionic conductivity is preferable because rate performance is improved.

According to the first embodiment, a composite electrolyte is provided. The composite electrolyte has a lithium ion conductivity of 1 × 10 ⁻¹⁰ S / cm or more at 25 ° C., and includes an inorganic compound particle containing a solvent, an organic electrolyte, and a binder, and the average particle diameter of the inorganic compound particle is It is 0.1 micrometer or more and less than 5 micrometers, and the weight ratio of the solvent with respect to the total weight of an inorganic compound particle and a solvent is 0.1 weight% or more and less than 8 weight%. Since such a composite electrolyte can shorten gelation time and lower electrode resistance, and can improve the conductivity of lithium ion, the secondary battery excellent in rate performance and low temperature performance can be implement | achieved.

(2nd embodiment)

According to the second embodiment, a secondary battery is provided. This secondary battery contains a positive electrode, a negative electrode, and the composite electrolyte which concerns on 1st Embodiment. The secondary battery may further include a positive electrode, a negative electrode, and an exterior member for accommodating the composite electrolyte. In addition, the secondary battery may further include a negative electrode terminal electrically connected to the negative electrode and a positive electrode terminal electrically connected to the positive electrode.

Hereinafter, the positive electrode, the negative electrode, the exterior member, the negative electrode terminal, and the positive electrode terminal will be described in detail.

(1) positive electrode

The positive electrode may include a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer may be formed on one side or both sides of the positive electrode current collector. The positive electrode active material layer may contain a positive electrode active material, and optionally a conductive agent and a binder.

As the positive electrode current collector, it is preferable to use aluminum foil or an aluminum alloy foil having a purity of 99% or more. As the aluminum alloy, an alloy containing at least one element selected from the group consisting of iron, magnesium, zinc, manganese and silicon in addition to aluminum is preferable. For example, Al-Fe alloys, Al-Mn-based alloys and Al-Mg-based alloys can obtain higher strength than aluminum.

It is preferable to make content of transition metals, such as nickel and chromium, in aluminum and an aluminum alloy into 100 ppm or less (including 0 ppm). For example, when Al-Cu type alloy is used, although intensity | strength becomes high, since corrosion resistance deteriorates, it is unsuitable as an electrical power collector.

Preferred aluminum purity is in the range of 99.99 to 99.0%. If it exists in this range, the fall of the cycle life resulting from high temperature of electrolyte by melt | dissolution of the impurity element which a positive electrode electrical power collector contains can be reduced.

Examples of the positive electrode active material include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt aluminum composite oxide, lithium nickel cobalt manganese composite oxide, spinel type lithium manganese nickel composite oxide, lithium manganese cobalt composite oxide, and olivine-type lithium iron phosphate (LiFePO ₄ ) and lithium manganese phosphate (LiMnPO ₄ ).

The positive electrode active material is, for example, Li _x Mn ₂ O ₄ or Li _x MnO _2, such as lithium manganese composite oxide, for example, Li _x Ni ₁ of the _{- y} Al _y O _2, such as lithium-nickel-aluminum composite oxide, such as Li of _x CoO ₂ lithium-cobalt composite oxide such as, for example, _{Li x Ni 1 -y- z Co y} Mn z O 2 , such as lithium nickel cobalt composite oxide, of for example, Li _x Mn _y Co _{1 - y} O _2, such as Spinel type lithium manganese nickel composite oxides such as lithium manganese cobalt composite oxides such as Li _x Mn _2-y Ni _y O ₄ , such as Li _x FePO ₄ , Li _x Fe _1-y Mn _y PO ₄ , Li _x CoPO _4, etc. raise the lithium phosphate having a blank structure, for example of may be mentioned fluorination of ferrous sulfate FeSO _{4 x} Li F. x satisfies 0 <x≤1 unless otherwise specified. y satisfies 0 <y <1, unless otherwise specified.

These are preferable because a high positive electrode potential is obtained. Especially, with lithium nickel aluminum composite oxide, lithium nickel cobalt manganese composite oxide, and lithium manganese cobalt composite oxide, reaction with electrolyte in high temperature environment can be suppressed and battery life can be improved significantly. Particularly preferred are lithium nickel cobalt manganese composite oxides represented by Li _x Ni _{1- y- z} Co _y Mn _z O ₂ (0 <x ≦ 1, 0 <y <0.5, 0 <z <0.5). By using lithium nickel cobalt manganese composite oxide, durability in high temperature environment can be improved more.

Examples of the conductive agent for increasing the electronic conductivity and suppressing the contact resistance with the current collector include acetylene black, carbon black, graphite and the like.

Examples of the binder for binding the active material and the conductive agent include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorine rubber.

The blending ratio of the positive electrode active material, the conductive agent and the binder in the positive electrode active material layer is 80% to 95% by weight of the positive electrode active material, 3% to 18% by weight of the conductive agent, and 2% by weight to 7% by weight of the binder. It is preferable to exist in the following ranges. If the conductive agent is 3% by weight or more, the above-described effects can be exhibited, and if it is 18% by weight or less, decomposition of the electrolyte on the surface of the conductive agent under high temperature storage can be reduced. If the binder is 2% by weight or more, sufficient electrode strength can be obtained, and if it is 7% by weight or less, the insulating portion of the electrode can be reduced.

A positive electrode can be produced by the following method, for example. First, a positive electrode active material, a conductive agent, and a binder are suspended in a solvent to prepare a slurry. This slurry is applied to one side or both sides of the positive electrode current collector. Subsequently, the applied slurry is dried to obtain a laminate of the positive electrode active material layer and the positive electrode current collector. Thereafter, the laminate is pressed. It is preferable that positive electrode press pressure exists in the range of 0.15 ton / mm-0.3 ton / mm. When positive electrode press pressure exists in this range, the adhesiveness (peel strength) of a positive electrode active material layer and a positive electrode collector becomes high, and the elongation rate of a positive electrode collector becomes 20% or less, and it is preferable. In this way, a positive electrode is produced. Alternatively, the positive electrode may be produced by the following method. First, a positive electrode active material, an electrically conductive agent, and a binder are mixed and a mixture is obtained. Subsequently, the mixture is molded into pellets. Subsequently, by placing these pellets on the positive electrode current collector, a positive electrode can be obtained.

(2) negative electrode

The negative electrode may include a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer may be formed on one side or both sides of the negative electrode current collector. The negative electrode active material layer may contain a negative electrode active material, and optionally a conductive agent and a binder.

As the negative electrode current collector, a material which is electrochemically stable at lithium occlusion and release potential of the negative electrode active material is used. The negative electrode current collector is preferably made from copper, nickel, stainless steel or aluminum, or an aluminum alloy containing at least one element selected from Mg, Ti, Zn, Mn, Fe, Cu, and Si. It is preferable that the thickness of a negative electrode electrical power collector exists in the range of 5 micrometers or more and 20 micrometers or less. The negative electrode current collector having such a thickness can balance the strength of the negative electrode and the weight reduction.

The negative electrode active material is contained in the negative electrode in the form of particles, for example. The negative electrode active material particles may be single primary particles, secondary particles that are aggregates of primary particles, or a mixture of single primary particles and secondary particles. From the viewpoint of densification, the negative electrode active material layer preferably contains 5 to 50% by volume of primary particles. The shape of a primary particle is not specifically limited, For example, it can be set as spherical shape, an ellipse shape, a flat shape, fibrous form.

Examples of the negative electrode active material include carbon materials, graphite materials, lithium alloy materials, metal oxides, and metal sulfides. Among them, lithium titanium oxides in which the occlusion and release potentials of lithium ions are in the range of 1 V to 3 V on the basis of lithium potential, It is preferable to select the negative electrode active material of at least one titanium-containing oxide selected from titanium oxide, niobium titanium oxide, and lithium sodium niobium titanium oxide.

Spinel structure lithium titanium oxide represented by the general formula Li _{4 + x} Ti ₅ O ₁₂ (x is −1 ≦ x ≦ 3) as the lithium titanium oxide, and Li _{2 + x} Ti ₃ O ₇ as the ramsdelite structure lithium titanium oxide , Li _{1 + x} Ti ₂ O ₄ , Li _{1.1 + x} Ti _{1 . 8 O 4, Li 1 .07+ x} Ti 1. Lithium titanium oxide such as ₈₆ O ₄ , Li _x TiO ₂ (x is 0 ≦ x), a monoclinic structure represented by the general formula Li _x TiO ₂ (0 ≦ x) (TiO ₂ (B) as a structure before charging), Titanium oxide with rutile structure and anatase structure (TiO ₂ and niobium titanium oxide as the charge structure are Li _a TiM _b Nb _{2 ± β} O _{7 ± σ} (0≤a≤5, 0≤b≤0.3, 0≤β≤ 0.3, 0 ≦ σ ≦ 0.3, and M are represented by at least one element selected from the group consisting of Fe, V, Mo, and Ta. These may be used alone or in combination. Is a spinel structure lithium titanium oxide represented by the general formula Li _{4 + x} Ti ₅ O ₁₂ (x is −1 ≦ x ≦ 3.) By using these titanium-containing oxides, aluminum is used instead of copper foil for the negative electrode current collector. The foil can be used, the weight and the cost can be reduced, and it is advantageous to the bipolar electrode structure.

Negative electrode active material particles, and the average particle diameter of 1㎛ or less, and preferably a specific surface area in BET method using N ₂ adsorption in the range of 3m ² / g to 200m ² / g. Thereby, affinity with the electrolyte of a negative electrode can be improved.

The reason for defining the specific surface area of a negative electrode in the said range is demonstrated. When the specific surface area is less than 3 m ² / g, the aggregation of the particles is remarkable, the affinity between the negative electrode and the electrolyte is low, and the interface resistance of the negative electrode is increased. As a result, output characteristics and charge / discharge cycle characteristics are deteriorated. On the other hand, if the specific surface area exceeds 50 m ² / g, the distribution of the electrolyte may be biased toward the negative electrode, which may lead to the shortage of the electrolyte in the positive electrode, and thus the output characteristics and the charge / discharge cycle characteristics cannot be improved. The more preferable range of specific surface area is 5-50 m <^2> / g. Here, the specific surface area of a negative electrode means the surface area per 1g of negative electrode active material layers (excluding the weight of an electrical power collector). The negative electrode active material layer is a porous layer containing a negative electrode active material, a conductive agent, and a binder supported on a current collector.

The porosity (excluding the current collector) of the negative electrode is preferably in the range of 20 to 50%. Thereby, it is excellent in the affinity of a negative electrode and electrolyte, and a high density negative electrode can be obtained. The more preferable range of porosity is 25 to 40%.

As the conductive agent, for example, a carbon material can be used. As a carbon material, acetylene black, carbon black, coke, carbon fiber, graphite, aluminum powder, TiO, etc. are mentioned, for example. More preferably, the coke, graphite, and TiO powder with an average particle diameter of 10 micrometers or less whose heat processing temperature is 800 degreeC-2000 degreeC, and carbon fiber whose average fiber diameter are 1 micrometer or less are preferable. The BET specific surface area due to N ₂ adsorption of the carbon material is preferably 10 m ² / g or more.

Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine rubber, styrene butadiene rubber, core shell binder, and the like.

It is preferable to make the compounding ratio of the active material, electrically conductive agent, and binder of the said negative electrode into the range of 80-95 weight% of negative electrode active materials, 3-18 weight% of conductive agents, and 2-7 weight% of binders.

A negative electrode can be produced by the following method, for example. First, a negative electrode active material, a conductive agent, and a binder are suspended in a suitable solvent to prepare a slurry. Subsequently, this slurry is applied to one side or both sides of the negative electrode current collector. The negative electrode active material layer is formed by drying the coating film on the negative electrode current collector. Thereafter, the negative electrode current collector and the negative electrode active material layer formed thereon are pressed. As a negative electrode active material layer, you may use what formed the negative electrode active material, the electrically conductive agent, and the binder in pellet form.

(3) exterior member

As the exterior member, for example, a container containing a laminate film or a metal container can be used.

The thickness of a laminate film is 0.5 mm or less, for example, Preferably it is 0.2 mm or less.

As the laminate film, a multilayer film including a plurality of resin layers and a metal layer interposed between these resin layers is used. The resin layer contains polymer materials, such as polypropylene (PP), polyethylene (PE), nylon, and polyethylene terephthalate (PET), for example. It is preferable that a metal layer contains aluminum foil or aluminum alloy foil for weight reduction. The laminate film can be molded into the shape of the exterior member by sealing by thermal fusion.

The wall thickness of a metal container is 1 mm or less, for example, More preferably, it is 0.5 mm or less, More preferably, it is 0.2 mm or less.

The metal container is made from aluminum or an aluminum alloy, for example. It is preferable that an aluminum alloy contains elements, such as magnesium, zinc, and a silicon. When an aluminum alloy contains transition metals, such as iron, copper, nickel, and chromium, it is preferable that the content is 100 ppm or less.

The shape of the exterior member is not particularly limited. The shape of the exterior member may be, for example, flat (thin), rectangular, cylindrical, coin, or button. The exterior member may be, for example, a small battery exterior member mounted on a portable electronic device or the like, a large battery exterior member mounted on a vehicle such as a two-wheeled or four-wheeled vehicle, a rail transport vehicle, or the like depending on the battery dimensions.

(4) negative terminal

The negative electrode terminal may be formed of a material which is electrochemically stable at the Li occlusion release potential of the above-described negative electrode active material and has conductivity. Specifically, as the material of the negative electrode terminal, an aluminum alloy containing at least one element selected from the group consisting of copper, nickel, stainless steel or aluminum, or Mg, Ti, Zn, Mn, Fe, Cu, and Si is used. Can be mentioned. As a material of a negative electrode terminal, it is preferable to use aluminum or an aluminum alloy. In order to reduce the contact resistance with a negative electrode electrical power collector, it is preferable that a negative electrode terminal contains the same material as a negative electrode electrical power collector.

(5) positive electrode terminal

The positive electrode terminal is formed of a material that is electrically stable and conductive in the range (vs. Li / Li +) in which the potential with respect to the redox potential of lithium is 3.0 V or more and 4.5 V or less. As a material of a positive electrode terminal, aluminum alloy containing aluminum or at least 1 sort (s) of element chosen from the group which consists of Mg, Ti, Zn, Mn, Fe, Cu, and Si is mentioned. In order to reduce the contact resistance with a positive electrode electrical power collector, it is preferable that a positive electrode terminal is formed with the same material as a positive electrode electrical power collector.

Next, the secondary battery which concerns on this embodiment is demonstrated more concretely, referring drawings.

1 is a cross-sectional view schematically showing an example of a secondary battery according to a second embodiment. FIG. 2 is an enlarged cross-sectional view of part A of the secondary battery illustrated in FIG. 1.

The secondary battery 100 shown in FIG. 1 and FIG. 2 includes the bag-shaped exterior member 2 shown in FIG. 1 and the electrode group 1 shown in FIGS. 1 and 2. The secondary battery 100 may further include a nonaqueous electrolyte. The electrode group 1 is housed in the exterior member 2. When the secondary battery 100 includes the nonaqueous electrolyte, the nonaqueous electrolyte is held in the electrode group 1.

The bag-shaped exterior member 2 includes a laminate film including two resin layers and a metal layer interposed therebetween.

As shown in FIG. 1, the electrode group 1 is a flat wound electrode group. As shown in FIG. 2, the flat wound electrode group 1 includes a negative electrode 3, a composite electrolyte layer 4, and a positive electrode 5. The composite electrolyte layer 4 is interposed between the negative electrode 3 and the positive electrode 5.

The negative electrode 3 includes the negative electrode current collector 3a and the negative electrode active material layer 3b. As for the part located in the outermost part of the wound electrode group 1 among the negative electrodes 3, as shown in FIG. 2, the negative electrode active material layer 3b is formed only in the inner surface side of the negative electrode collector 3a. In other parts of the negative electrode 3, the negative electrode active material layer 3b is formed on both surfaces of the negative electrode current collector 3a.

The positive electrode 5 includes the positive electrode current collector 5a and the positive electrode active material layer 5b formed on both surfaces thereof.

As shown in FIG. 1, the negative electrode terminal 6 and the positive electrode terminal 7 are located near the outer circumferential end portion of the wound electrode group 1. This negative electrode terminal 6 is connected to a part of the negative electrode current collector 3a of the negative electrode 3 located at the outermost part. In addition, the positive electrode terminal 7 is connected to the positive electrode current collector 5a of the positive electrode 5 located at the outermost angle. These negative electrode terminal 6 and the positive electrode terminal 7 extend outward from the opening of the bag-shaped exterior member 2.

The wound electrode group 1 is sealed by heat-sealing the opening part of the bag-shaped exterior member 2 between the negative electrode terminal 6 and the positive electrode terminal 7.

The secondary battery of this embodiment is not limited to the secondary battery of the structure shown in FIG. 1 and FIG. 2, For example, the battery of the structure shown in FIG. 3 and FIG. 4 may be sufficient.

3 is a partially cutaway perspective view schematically showing another example of the secondary battery according to the second embodiment. 4 is an enlarged cross-sectional view of a portion B of the secondary battery illustrated in FIG. 3.

The secondary battery 100 shown in FIG. 3 and FIG. 4 includes the electrode group 11 shown in FIGS. 3 and 4 and the exterior member 12 shown in FIG. 3. The secondary battery 100 may be provided with a nonaqueous electrolyte. The electrode group 11 is housed in the exterior member 12. When the secondary battery 100 includes a nonaqueous electrolyte, the nonaqueous electrolyte is held by the electrode group 11.

The exterior member 12 includes a laminate film including two resin layers and a metal layer interposed therebetween.

The electrode group 11 is a stacked electrode group as shown in FIG. 4. The stacked electrode group 11 has a structure in which the positive electrode 13 and the negative electrode 14 are alternately stacked with the composite electrolyte 15 interposed therebetween.

The electrode group 11 includes a plurality of positive electrodes 13. Each of the plurality of positive electrodes 13 includes a positive electrode current collector 13a and a positive electrode active material layer 13b supported on both surfaces of the positive electrode current collector 13a. In addition, the electrode group 11 includes a plurality of negative electrodes 14. Each of the plurality of negative electrodes 14 includes a negative electrode current collector 14a and a negative electrode active material layer 14b supported on both surfaces of the negative electrode current collector 14a. One side of the negative electrode current collector 14a of each negative electrode 14 protrudes from the negative electrode 14. The protruding negative electrode current collector 14a is electrically connected to the strip-shaped negative electrode terminal 16. The tip of the strip-shaped negative electrode terminal 6 is drawn out of the exterior member 12. In addition, although not shown, in the positive electrode collector 13a of the positive electrode 13, the side located on the opposite side to the protruding side of the negative electrode collector 14a protrudes from the positive electrode 13. The positive electrode current collector 13a protruding from the positive electrode 13 is electrically connected to the strip-shaped positive electrode terminal 7. The tip of the strip-shaped positive electrode terminal 7 is located on the side opposite to the negative electrode terminal 6 and is drawn out of the exterior member 12.

As described above, the secondary battery according to the present embodiment may have a monopolar structure or a bipolar structure as shown in FIG. 5.

The secondary battery 100 shown in FIG. 5 is comprised as follows.

This secondary battery 100 is provided with the electrode group 11 and the exterior member 12 which accommodates this electrode group 11.

The electrode group 11 includes a first laminate in which a positive electrode active material layer 5b is formed on one surface of the current collector 8 and a negative electrode active material layer 3b is formed on the other surface. The composite electrolyte layer 4 is formed on the negative electrode active material 3b included in the first laminate.

Moreover, the 2nd laminated body which the one end part of the electrode group 11, for example, the upper end part shown in FIG. 5 includes the negative electrode active material layer 3b and the composite electrolyte layer 4 on one side of the electrical power collector 8 ) Is a laminate provided in this order. The positive electrode terminal 7 is electrically connected to the current collector 8 included in the second laminate. Although not shown, the positive electrode terminal 7 is drawn out from the exterior member 12 to the outside.

In addition, the 3rd laminated body which the other edge part of the electrode group 11, for example, the lower end part shown in FIG. 5 is a laminated body in which the positive electrode active material 5b was provided in the single side | surface of the electrical power collector 8 is used. The negative electrode terminal 6 is electrically connected to the current collector 8 included in the third laminate. Although not shown, the negative electrode terminal 6 is drawn out from the exterior member 12 to the outside.

The electrode group 11 having the bipolar electrode structure shown in FIG. 5 is configured by stacking a second laminate, a plurality of first laminates, and a third laminate in this order. The number of 1st laminated bodies can be changed suitably according to a battery design.

A secondary battery having a bipolar electrode structure is compact and has a high capacity, and can achieve excellent life performance, thermal stability, and electrochemical stability.

The secondary battery according to the present embodiment may constitute an assembled battery. The assembled battery includes a plurality of secondary batteries according to the present embodiment.

In the assembled battery according to the embodiment, each unit cell may be electrically connected in series or in parallel, or may be disposed in combination of series connection and parallel connection.

An example of the assembled battery according to the embodiment will be described with reference to the drawings.

6 is a perspective view schematically showing an example of the assembled battery according to the embodiment. The assembled battery 200 shown in FIG. 6 includes five unit cells 100, four bus bars 21, a positive electrode side lead 22, and a negative electrode side lead 23. Each of the five unit cells 100 is a secondary battery according to the present embodiment.

The bus bar 21 connects the negative electrode terminal 6 of one unit cell 100 with the positive electrode terminal 7 of the unit cell 100 located in the vicinity of the unit cell 100. In this way, the five unit cells 100 are connected in series by four bus bars 21. That is, the battery pack 200 of FIG. 6 is a battery pack of five series.

As shown in FIG. 6, the positive electrode terminal 7 of the unit cell 100 located at one end of the five unit cells 100 is connected to the positive electrode side lead 22 for external connection. Moreover, the negative electrode terminal 6 of the unit cell 100 located at the other end among the five unit cells 100 is connected to the negative electrode side lead 23 for external connection.

The secondary battery according to the second embodiment includes the composite electrolyte according to the first embodiment. Therefore, this secondary battery is excellent in rate performance and low temperature performance.

(Third embodiment)

According to the third embodiment, a battery pack is provided. This battery pack is provided with the assembled battery which consists of a secondary battery or some secondary battery which concerns on 2nd Embodiment.

The battery pack may further include a protection circuit. The protection circuit has a function of controlling charge and discharge of the secondary battery. Or you may use the circuit contained in the apparatus (for example, an electronic device, an automobile, etc.) using a battery pack as a power supply as a protection circuit of a battery pack.

The battery pack may further include an external terminal for power supply. The external terminal for electricity supply is for outputting the electric current from a secondary battery to the outside, and / or for inputting the electric current from the outside to a secondary battery. In other words, when the battery pack is used as a power source, current is supplied to the outside through an external terminal for power supply. In addition, when charging the battery pack, a charging current (including regenerative energy of power of an automobile or the like) is supplied to the battery pack through an external terminal for power supply.

Next, an example of the battery pack which concerns on 3rd Embodiment is demonstrated, referring drawings.

7 is an exploded perspective view schematically showing an example of the battery pack according to the third embodiment. FIG. 8 is a block diagram showing an example of an electric circuit of the battery pack shown in FIG. 7.

The battery pack 300 shown in FIG. 7 and FIG. 8 includes an accommodating container 31, a lid 32, a protective sheet 33, an assembled battery 200, a printed wiring board 34, and wiring. 35 and an insulating plate (not shown) are provided.

The storage container 31 is comprised so that the protective sheet 33, the assembled battery 200, the printed wiring board 34, and the wiring 35 can be accommodated. The cover 32 accommodates the assembled battery 200 and the like by covering the housing container 31. Although not shown, the accommodating container 31 and the lid 32 are provided with an opening, a connection terminal, or the like for connecting to an external device or the like.

The protective sheet 33 is disposed on both inner surfaces in the long side direction of the storage container 31 and on one inner side in the short side direction of the storage container 31. The printed wiring board 34 is provided on the other inner side surface of the accommodating container 31 in the short side direction. The protective sheet 33 contains resin or rubber, for example.

The assembled battery 200 includes a plurality of unit cells 100, a positive electrode side lead 22, a negative electrode side lead 23, and an adhesive tape 24. The assembled battery 200 may be one unit cell 100.

The unit cell 100 has a structure described with reference to FIGS. 1 and 2, for example. At least one of the plurality of unit cells 100 is a secondary battery according to the second embodiment. The plurality of unit cells 100 are stacked so that the negative electrode terminal 6 and the positive electrode terminal 7 extending outward are in the same direction. Each of the plurality of unit cells 100 is electrically connected in series as shown in FIG. 8. The plurality of unit cells 100 may be electrically connected in parallel, or may be connected in a combination of series connection and parallel connection. When the plurality of unit cells 100 are connected in parallel, the battery capacity is increased as compared with the case where the plurality of unit cells 100 are connected in series.

The adhesive tape 24 fastens the some unit cell 100. Instead of the adhesive tape 24, a plurality of unit cells 100 may be fixed using a heat shrink tape. In this case, the protective sheet 33 is arrange | positioned on both sides of the assembled battery 200, the heat shrink tape is wound around, and the heat shrink tape is heat shrinked, and the some unit cell 100 is bound.

One end of the positive electrode side lead 22 is connected to the positive electrode terminal 7 of the single cell 100 located at the lowest layer in the laminate of the single cell 100. One end of the negative electrode side lead 23 is connected to the negative electrode terminal 6 of the single cell 100 located on the uppermost layer in the stacked body of the single cell 100.

The printed wiring board 34 includes a positive electrode side connector 341, a negative electrode side connector 342, a thermistor 343, a protection circuit 344, wirings 345 and 346, and an external terminal for power transmission ( 347, positive side wiring 348a, and negative side wiring 348b. One main surface of the printed wiring board 34 faces the surface where the negative electrode terminal 6 and the positive electrode terminal 7 protrude in the assembled battery 200. An insulating plate (not shown) is interposed between the printed wiring board 34 and the battery pack 200.

The through hole is provided in the positive electrode side connector 341. The other end of the positive electrode side lead 22 is inserted into the through hole, whereby the positive electrode side connector 341 and the positive electrode side lead 22 are electrically connected. The through hole is provided in the negative electrode side connector 342. The other end of the negative electrode side lead 23 is inserted into the through hole, so that the negative electrode connector 342 and the negative electrode side lead 23 are electrically connected to each other.

The thermistor 343 is fixed to one main surface of the printed wiring board 34. The thermistor 343 detects the temperature of each unit cell 100 and transmits the detection signal to the protection circuit 344.

The external terminal 347 for electricity supply is fixed to the other main surface of the printed wiring board 34. The external terminal 347 for electricity transmission is electrically connected with the apparatus which exists outside the battery pack 300. FIG.

The protection circuit 344 is fixed to the other main surface of the printed wiring board 34. The protection circuit 344 is connected to the external terminal 347 for electricity supply via the positive side wiring 348a. The protection circuit 344 is connected to the external terminal 347 for electricity supply through the negative side wiring 348b. The protection circuit 344 is electrically connected to the positive electrode side connector 341 via the wiring 345. The protection circuit 344 is electrically connected to the negative electrode side connector 342 through the wiring 346. In addition, the protection circuit 344 is electrically connected to each of the plurality of unit cells 100 through the wiring 35.

The protection circuit 344 controls charging and discharging of the plurality of unit cells 100. In addition, the protection circuit 344 is connected to the protection circuit 344 and the external device based on the detection signal transmitted from the thermistor 343 or the detection signal transmitted from each unit cell 100 or the battery pack 200. It cuts off the electrical connection of the external terminal 347 for electricity supply.

As a detection signal transmitted from the thermistor 343, the signal which detected that the temperature of the unit cell 100 is more than predetermined temperature is mentioned, for example. As a detection signal transmitted from each unit cell 100 or the assembled battery 200, the signal which detected the overcharge, overdischarge, and the overcurrent of the unit cell 100 is mentioned, for example. When overcharge etc. are detected with respect to each unit cell 100, a battery voltage may be detected and a positive electrode potential or a negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each unit cell 100.

As the protection circuit 344, a circuit included in an apparatus (eg, an electronic device, a car, etc.) using the battery pack 300 as a power source may be used.

Such a battery pack 300 is used for the use which is required to be excellent in cycling performance, for example when taking out a large electric current. Specifically, the battery pack 300 is used, for example, as a power source for an electronic device, a stationary battery, a vehicle-mounted battery for a vehicle, or a battery for a railroad vehicle. As an electronic device, a digital camera is mentioned, for example. This battery pack 300 is particularly suitably used as a vehicle-mounted battery.

In addition, the battery pack 300 includes an external terminal 347 for power supply as described above. Therefore, the battery pack 300 outputs the current from the battery pack 200 to an external device through the external terminal 347 for power transmission, and transmits the current from the external device to the battery pack 200. You can enter In other words, when the battery pack 300 is used as a power source, the current from the battery pack 200 is supplied to an external device through an external terminal 347 for power supply. In addition, when charging the battery pack 300, the charging current from an external device is supplied to the battery pack 300 via the external terminal 347 for electricity supply. When the battery pack 300 is used as a vehicle-mounted battery, the power regenerative energy of the vehicle can be used as the charging current from the external device.

In addition, the battery pack 300 may include a plurality of battery packs 200. In this case, the plurality of battery packs 200 may be connected in series, may be connected in parallel, or may be connected in combination of series connection and parallel connection. Note that the printed wiring board 34 and the wiring 35 may be omitted. In this case, you may use the positive electrode side lead 22 and the negative electrode side lead 23 as an external terminal for electricity supply.

The battery pack according to the third embodiment includes the secondary battery according to the second embodiment. Therefore, this battery pack can achieve the outstanding rate performance and low temperature performance.

(4th embodiment)

According to the fourth embodiment, a vehicle is provided. This vehicle is equipped with the battery pack which concerns on 3rd Embodiment.

In the vehicle according to the fourth embodiment, the battery pack recovers power regenerative energy of the vehicle, for example.

Examples of the vehicle include, for example, two- to four-wheel hybrid electric vehicles, two- to four-wheel electric vehicles, and assist bicycles and railway vehicles.

The mounting position of the battery pack in the vehicle is not particularly limited. For example, when the battery pack is mounted in an automobile, the battery pack can be mounted in the engine compartment, the rear of the vehicle body, or under the seat of the vehicle.

Next, an example of the vehicle which concerns on embodiment is demonstrated, referring drawings.

9 is a sectional views schematically showing an example of a vehicle according to the fourth embodiment.

The vehicle 400 shown in FIG. 9 includes a vehicle body 40 and a battery pack 300 according to the third embodiment. The vehicle 400 shown in FIG. 9 is a four-wheeled vehicle.

This vehicle 400 may be equipped with a plurality of battery packs 300. In this case, the battery pack 300 may be connected in series, may be connected in parallel, or may be connected in combination of a serial connection and a parallel connection.

The battery pack 300 is mounted in an engine room located in front of the vehicle body 40. The mounting position of the battery pack 300 is not particularly limited. The battery pack 300 may be mounted behind the vehicle body 40 or under the seat. The battery pack 300 can be used as a power source for the vehicle 400.

Next, an embodiment of the vehicle according to the fourth embodiment will be described with reference to FIG. 10. 10 is a diagram schematically showing another example of the vehicle according to the fourth embodiment. The vehicle 400 shown in FIG. 10 is an electric vehicle.

The vehicle 400 illustrated in FIG. 10 includes a vehicle ECU (ECU) electric control unit (ECU) 42 which is an upper control means of the vehicle main body 40, the vehicle power source 41, and the vehicle power source 41. And an external terminal (terminal for connecting to an external power supply) 43, an inverter 44, and a drive motor 45.

The vehicle 400 mounts a vehicle power source 41, for example, in an engine room, behind a vehicle body, or under a seat. In addition, in the vehicle 400 shown in FIG. 10, the mounting location of the vehicle power supply 41 is shown schematically.

The vehicle power supply 41 includes a plurality (for example, three) of battery packs 300a, 300b, and 300c, a battery management unit (BMU) 411, and a communication bus 412. have.

The three battery packs 300a, 300b, and 300c are electrically connected in series. The battery pack 300a includes an assembled battery 200a and an assembled battery monitoring device (VTM: Voltage Temperature Monitoring) 301a. The battery pack 300b includes an assembled battery 200b and an assembled battery monitoring device 301b. The battery pack 300c includes an assembled battery 200c and an assembled battery monitoring device 301c. The battery packs 300a, 300b, and 300c can be removed independently, and can be replaced with other battery packs 300.

Each of the battery packs 200a to 200c includes a plurality of unit cells connected in series. At least one of the plurality of unit cells is a secondary battery according to the second embodiment. The battery packs 200a to 200c charge and discharge through the positive electrode terminal 413 and the negative electrode terminal 414, respectively.

The battery management device 411 communicates between the battery pack monitoring devices 301a to 301c in order to collect information on the maintenance of the vehicle power supply 41, and includes the battery packs 200a to 200 included in the vehicle power supply 41. Information about the voltage and temperature of the unit cell 100 included in the 200c is collected.

The communication bus 412 is connected between the battery management device 411 and the battery pack monitoring devices 301a to 301c. The communication bus 412 is comprised so that one set of communication lines may be shared by several node (battery management apparatus and one or more battery pack monitoring apparatus). The communication bus 412 is a communication bus configured based on, for example, a Control Area Network (CAN) standard.

The battery pack monitoring devices 301a to 301c measure the voltages and temperatures of individual cells constituting the battery packs 200a to 200c based on a command by the communication from the battery management device 411. However, the temperature can be measured only a few places for one assembled battery, and it is not necessary to measure the temperature of all the unit cells.

The vehicle power supply 41 may have an electromagnetic contactor (for example, a switch device 415 shown in FIG. 10) for turning on and off the connection between the positive electrode terminal 413 and the negative electrode terminal 414. The switch device 415 includes a precharge switch (not shown) that is turned on when charging the battery packs 200a to 200c is performed, and a main switch (not shown) that is turned on when the battery output is supplied to a load. It is included. The precharge switch and the main switch are provided with a relay circuit (not shown) which is turned on or off by a signal supplied to a coil arranged near the switch element.

The inverter 44 converts the input DC voltage into the high voltage of the three-phase alternating current (AC) for motor drive. The three-phase output terminal of the inverter 44 is connected to the input terminal of each of the three phases of the drive motor 45. The inverter 44 controls the output voltage based on the control signal from the battery management device 411 or the vehicle ECU 42 for controlling the whole vehicle operation.

The drive motor 45 rotates by the electric power supplied from the inverter 44. This rotation is transmitted to the axle and drive wheels W, for example, via a differential gear unit.

In addition, although not shown, the vehicle 400 is equipped with a regenerative brake mechanism. The regenerative brake mechanism rotates the drive motor 45 when the vehicle 400 is braked, and converts the kinetic energy into regenerative energy as electrical energy. The regenerative energy recovered by the regenerative brake mechanism is input to the inverter 44 and converted into a direct current. DC current is input to the vehicle power supply 41.

One terminal of the connection line L1 is connected to the negative electrode terminal 414 of the vehicle power supply 41 through a current detection unit (not shown) in the battery management device 411. The other terminal of the connection line L1 is connected to the negative electrode input terminal of the inverter 44.

One terminal of the connection line L2 is connected to the positive electrode terminal 413 of the vehicle power supply 41 via the switch device 415. The other terminal of the connection line L2 is connected to the positive electrode input terminal of the inverter 44.

The external terminal 43 is connected to the battery management device 411. The external terminal 43 can be connected to an external power supply, for example.

The vehicle ECU 42 cooperatively controls the battery management device 411 with other devices in response to an operation input of a driver or the like to manage the entire vehicle. Between the battery management device 411 and the vehicle ECU 42, data transmission relating to maintenance of the vehicle power source 41, such as the remaining capacity of the vehicle power source 41, is performed by the communication line.

The vehicle according to the fourth embodiment includes the battery pack according to the third embodiment. Therefore, according to this embodiment, the vehicle equipped with the battery pack which can achieve the outstanding rate performance and low temperature performance can be provided.

EXAMPLE

Although an Example is described below, embodiment is not limited to the Example described below.

(Example 1)

The secondary battery of the monopolar structure was produced with the following procedures.

<Production of positive electrode>

5% by weight of lithium manganese oxide (LiMn ₂ O ₄ ) having a spinel structure with an average particle diameter of 10 nm and graphite powder having an average particle diameter of 6 μm as a positive electrode active material, and 3% by weight of PVdF with respect to the entire positive electrode as a binder as a positive electrode active material Each was combined and dispersed in an N-methylpyrrolidone (NMP) solvent to prepare a slurry. Then, this slurry was apply | coated to the single side | surface of the aluminum alloy foil (99% of purity) of thickness 12micrometer, it dried, and the positive electrode was produced through the press process. The produced positive electrode had a thickness of the positive electrode active material layer on one side of 67 µm and an electrode density of 2.7 g / cm ³ .

<Production of negative electrode>

Li ₄ Ti ₅ O ₁₂ particles having an average particle diameter of 0.6 μm and a specific surface area of 10 m ² / g as a negative electrode active material, graphite powder having an average particle diameter of 6 μm as a conductive agent, and PVdF as a binder in a weight ratio of 95: 3: Formulated at 2 and dispersed in N-methylpyrrolidone (NMP) solvent. This dispersion liquid was stirred over 2 hours of stirring time using the ball mill (rotation speed 1000rpm), and the slurry was prepared. The obtained slurry was apply | coated to the single side | surface of the aluminum alloy foil (purity 99.3%) of thickness 15micrometer, it dried, and the negative electrode was produced by going through the hot press process. The produced negative electrode had a thickness of the negative electrode active material layer on one side of 59 μm and an electrode density of 2.2 g / cm ³ . In addition, the negative electrode porosity except for the electrical power collector of this negative electrode was 35%.

<Production of Composite Electrolyte>

First, Li ₇ La ₃ Zr ₂ O ₁₂ (LLZ) particles were prepared as inorganic compound particles, and ground grinding was performed such that the average particle diameter (diameter) of the primary particles of these particles was 0.1 μm. Subsequently, the crushed LLZ particles were dispersed in an N-methyl-2-pyrrolidone (NMP) solution containing 0.5 wt% of PVdF binder. This dispersion was applied onto the positive electrode active material layer and the negative electrode active material layer, and dried to form a solid electrolyte layer.

Subsequently, a mixed solvent of propylene carbonate and diethyl carbonate in which 1.2 M of LiPF ₆ was dissolved (volume ratio 1: 2) and a polymer body (2% by weight) of polyacrylonitrile (PAN) as a gelling agent were used. The solution containing was impregnated with the said solid electrolyte layer, the positive electrode active material layer, and the negative electrode active material layer. Thus, the gelled composite electrolyte was produced by heating the positive electrode and negative electrode which impregnated the solution at 60 degreeC over 25 hours. The amount of organic components in the electrode and the composite electrolyte at this time were adjusted to be 3% and 4% by weight ratio, respectively. The organic component was a mixed solvent of propylene carbonate and diethyl carbonate in which 1.2 M of LiPF ₆ was dissolved (volume ratio 1: 2), and a polymer body of polyacrylonitrile (PAN) as a gelling agent (2 weight). %) Means a solution containing. In addition, the weight ratio of the inorganic particle contained in a composite electrolyte, the gelling agent as a binder, and the organic component was 94.3: 1.9: 3.8.

<Measurement of Ionic Conductivity of Composite Electrolyte>

A composite electrolyte having a constant film thickness was fabricated on a 15 µm aluminum alloy foil (99.3% purity) to obtain an ion block electrode. AC impedance measurement of the produced composite electrolyte can be performed, and ion conductivity can be calculated from the obtained resistance value.

<Production of Secondary Battery>

The positive electrode and negative electrode obtained above were laminated | stacked so that the composite electrolyte provided on the positive electrode active material layer and the composite electrolyte provided on the negative electrode active material layer might face, and the laminated body was obtained. Subsequently, this laminated body was wound by the spiral winding so that a negative electrode might be located in outermost periphery, and the electrode group was produced. The flat electrode group was produced by heat-pressing this at 90 degreeC. The obtained electrode group was accommodated in the thin metal can containing the stainless steel of thickness 0.25mm. In addition, the metal can is provided with a valve for leaking gas when the internal pressure is 2 atm or higher.

<Rate performance evaluation>

The cells were subjected to a rate test under 25 ° C. environment. In charging and discharging, first, the battery was charged to 1 A up to 3.0 V, then discharged to 1 A up to 1.7 V to confirm the battery capacity, and then the discharge current was discharged to 20 A to confirm the battery capacity.

<Low Temperature Performance Evaluation>

In order to evaluate the characteristics at low temperatures, first, the battery was charged to 1 A up to 3.0 V under 25 ° C. environment. Then, after waiting 5 hours in a 25 degreeC or -30 degreeC environment, it discharged to 1.7 A to 1.7V, and confirmed the battery capacity. The discharge capacity retention rate at -30 ° C against the measured discharge capacity of 25 ° C was evaluated.

<Weight measurement of the solvent contained in the inorganic compound particles>

The positive electrode and the negative electrode were taken out from the produced secondary battery, and TG measurement and DSC measurement were performed in accordance with the method described in the first embodiment. These results are shown in FIG. 11 and FIG. 11 is a graph showing the results of thermogravimetric measurements. 12 is a graph showing the results of differential scanning calorimetry. 11 and 12 also show measurement results of Example 7 and Comparative Example 1 described later.

It was 3 weight% from the measurement result shown in FIG. 11 and FIG. 12 when the weight of the said solvent was measured with respect to the total weight of the solvent which the inorganic compound particle and inorganic compound particle which concerns on Example 1 contain.

The above results are shown in Table 1 below. Table 1 also shows the results of Examples 2 to 9 and Comparative Examples 1 to 3 described later. In Table 1, the heat "calcination after grinding" has shown the baking conditions after grinding | pulverization of an inorganic compound particle. "-" Has shown that baking was not carried out. The heat of "solvent content" has shown the weight ratio of the said solvent with respect to the total weight of the solvent which an inorganic compound particle and an inorganic compound particle contain. The heat of "gelling time" has shown the time taken until the mixture of an organic electrolyte and a binder gelatinized. The column "25 degreeC rate performance 1C / 20C capacity retention rate" has shown the capacity retention rate of 1C discharge capacity with respect to the measured 20C discharge capacity. The heat of "low temperature performance -30 degreeC / 25 degreeC capacity retention rate" has shown the capacity retention rate of the discharge capacity in -30 degreeC with respect to the measured discharge capacity of 25 degreeC.

(Examples 2 to 5)

Except having used the inorganic compound particle of the kind shown in Table 1 as an inorganic compound particle, the composite electrolyte was produced by the method similar to what was described in Example 1, and the ion conductivity was measured.

Moreover, using this composite electrolyte, a secondary battery was produced in the same manner as described in Example 1, and the rate performance and the low temperature performance were evaluated.

(Example 6)

The composite electrolyte was prepared in the same manner as described in Example 1, except that the LLZ as the inorganic compound particles were ground by bead mill (wet) milling using pure water and calcined for 12 hours at a temperature of 500 ° C after the milling. Was prepared and the ion conductivity was measured. In addition, the beads rotation speed at the time of a crushing of a beads mill was 800 rpm, and grind | pulverized over 60 minutes by the flow volume of 30 ml / min.

Moreover, using this composite electrolyte, a secondary battery was produced in the same manner as described in Example 1, and the rate performance and the low temperature performance were evaluated.

(Example 7)

The composite electrolyte was prepared in the same manner as described in Example 1 except that the LLZ as the inorganic compound particles were pulverized by bead mill (wet) pulverization using ethanol and calcined for 12 hours at a temperature of 500 ° C. after pulverization. Was prepared and the ion conductivity was measured. In addition, the beads rotation speed at the time of a crushing of a beads mill was 800 rpm, and grind | pulverized over 60 minutes by the flow volume of 30 ml / min.

Moreover, using this composite electrolyte, a secondary battery was produced in the same manner as described in Example 1, and the rate performance and the low temperature performance were evaluated.

(Example 8)

The secondary battery of the bipolar structure was produced with the following procedures.

In order to investigate the battery performance by the secondary battery which has a bipolar electrode structure, the both sides of the positive electrode active material which formed the positive electrode active material layer of Example 1 on one side of the aluminum electrical power collector, and the negative electrode active material layer of Example 1 on the other side of the aluminum collector An electrode was produced. There, the solid electrolyte of Example 1 was coat | covered using the spray for coating on the surface of a positive electrode and a negative electrode. After that, a solution of a mixed solvent of propylene carbonate (PC) and diethyl carbonate (volume ratio 1: 2) and polyacrylonitrile polymer (2% by weight) in which 1 M of LiPF ₆ was dissolved before gelation was used as a positive electrode. It permeated into the space | gap of an active material layer and a negative electrode active material layer. Thereafter, the solution was gelated by heating to form a composite electrolyte, to prepare a secondary battery having a five-layer bipolar electrode structure.

The rate performance and low temperature performance of the secondary battery were evaluated by the method mentioned above.

(Comparative Example 1)

Except not firing after pulverizing the inorganic compound particles, a composite electrolyte was produced in the same manner as described in Example 6, and ionic conductivity was measured.

Moreover, using this composite electrolyte, a secondary battery was produced in the same manner as described in Example 1, and the rate performance and the low temperature performance were evaluated.

(Comparative Example 2)

A composite electrolyte was produced in the same manner as described in Example 7 except that firing was not performed after pulverizing the inorganic compound particles, and ionic conductivity was measured.

Moreover, using this composite electrolyte, a secondary battery was produced in the same manner as described in Example 1, and the rate performance and the low temperature performance were evaluated.

(Comparative Example 3)

A composite electrolyte was produced in the same manner as described in Example 6 except that baking after the pulverization of the inorganic compound particles was performed at a temperature of 100 ° C. for 12 hours, and ionic conductivity was measured.

Moreover, using this composite electrolyte, a secondary battery was produced in the same manner as described in Example 1, and the rate performance and the low temperature performance were evaluated.

(Comparative Example 4)

A composite electrolyte was produced in the same manner as described in Example 6 except that baking after the pulverization of the inorganic compound particles was performed at a temperature of 800 ° C. for 2 hours, and ionic conductivity was measured.

Moreover, using this composite electrolyte, a secondary battery was produced in the same manner as described in Example 1, and the rate performance and the low temperature performance were evaluated.

Table 1 shows the following.

From Examples 1 to 5, it can be seen that excellent rate performance and low temperature performance can be attained even if various kinds of inorganic compound particles are varied.

From the comparison of Examples 1, 6 and 7, and Comparative Examples 3 and 4, even when the grinding of the inorganic compound particles is performed by wet grinding, by firing at an appropriate temperature and time after the grinding of these particles, It turned out that it is possible to make solvent amount into 0.1 weight% or more and less than 8 weight%.

As shown in Example 8, even a bipolar structure secondary battery was able to achieve excellent rate performance and low temperature performance.

Comparing Example 1 with Comparative Examples 1 and 2, it can be seen that excellent rate performance and low temperature performance cannot be achieved unless the mixture of the organic electrolyte and the binder is gelled.

According to at least one embodiment and example described above, a composite electrolyte is provided. The composite electrolyte has a lithium ion conductivity of 1 × 10 ⁻¹⁰ S / cm or more at 25 ° C., and includes inorganic compound particles containing a solvent, an organic electrolyte, and a binder, and the total weight of the inorganic compound particles and the solvent. The weight ratio of the solvent with respect to is 0.1 weight% or more and less than 8 weight%. Therefore, a composite electrolyte capable of realizing a secondary battery having excellent rate performance and low temperature performance can be obtained.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the inventions described in the claims and their equivalents.

1: wound electrode group
2: exterior member
3: negative
3a: negative electrode current collector
3b: negative electrode active material layer
4: composite electrolyte layer
5: positive electrode
5a: positive electrode current collector
5b: positive electrode active material layer
6: negative electrode terminal
7: positive terminal
8: house
11: stacked electrode group
12: exterior member
13: positive electrode
13a: positive electrode current collector
13b: positive electrode active material layer
14: negative electrode
14a: negative electrode current collector
14b: negative electrode active material layer
21: bus bar
22: positive electrode side lead
23: negative electrode lead
24: adhesive tape
31: receiving container
32: cover
33: protective sheet
34: printed wiring board
35: wiring
40: vehicle body
41: car power
42: electric control device
43: external terminal
44: inverter
45: drive motor
100: secondary battery
200: battery
200a: battery pack
200b: battery pack
200c: battery pack
300: battery pack
300a: battery pack
300b: battery pack
300c: battery pack
301a: battery monitoring device
301b: battery monitoring device
301c: battery monitoring device
341: positive electrode side connector
342: negative electrode connector
343: thermistor
344: protection circuit
345: wiring
346: wiring
347: power supply external terminal
348a: plus side wiring
348b: negative side wiring
400: vehicle
411: battery management device
412: communication bus
413: positive electrode terminal
414: negative electrode terminal
415: switch device
L1: connection line
L2: connection line
W: drive wheel

Claims (14)

Inorganic compound particles containing a solvent having a lithium ion conductivity of 1 × 10 ⁻¹⁰ S / cm or more at 25 ° C.,
With organic electrolytes,
Including a binder,
The average particle diameter of the said inorganic compound particle is 0.1 micrometer or more and less than 5 micrometers,
The solvent is present on the inside and the surface of the inorganic compound particles,
The composite electrolyte with which the weight ratio of the said solvent with respect to the total weight of the said inorganic compound particle and the said solvent is 0.1 weight% or more and less than 8 weight%. The method of claim 1,
A composite electrolyte comprising a gel composition comprising the organic electrolyte and the binder. The method of claim 1,
The composite electrolyte of 0.1 weight% or more and 2 weight% or less of the weight ratio of the said solvent with respect to the total weight of the said inorganic compound particle and the said solvent. The method of claim 1,
The composite electrolyte of Claim 1 whose average particle diameter of the said inorganic compound particle is 0.1 micrometer or more and 2 micrometers or less. The method of claim 1,
The lithium ion conductivity of the inorganic compound particles is 2 × 10 ^-2 S / cm or less, composite electrolyte. The method of claim 1,
The inorganic compound particles are at least one selected from the group consisting of Li _{5 + x} A _y La _3-y M ₂ O ₁₂ (A is Ca, Sr and Ba, and M is at least one selected from the group consisting of Nb and Ta). X is 0 ≦ x <0.8, y is 0 ≦ y <2), Li ₃ M _2-x Zr ₂ O ₁₂ (M is at least one selected from the group consisting of Ta and Nb, and x is 0) _≦ x <0.8), Li _7-3x Al _x La ₃ Zr ₃ O ₁₂ (x is 0 ≦ x <0.8), and at least one selected from the group consisting of Li ₇ La ₃ Zr ₂ O ₁₂ , the composite Electrolyte. The method of claim 1,
The organic electrolyte includes at least one organic solvent selected from the group consisting of propylene carbonate, ethylene carbonate, diethyl carbonate and methyl ethyl carbonate. The method of claim 1,
The solvent is at least one selected from the group consisting of a polar organic solvent and a nonpolar organic solvent. Positive electrode,
Negative,
The secondary battery provided with the composite electrolyte in any one of Claims 1-8. The battery pack provided with the secondary battery of Claim 9. The method of claim 10,
The battery pack which further contains an external terminal for electricity supply, and a protection circuit. The method of claim 10,
A battery pack comprising a plurality of the secondary batteries, wherein the secondary batteries are electrically connected in series, in parallel, or in series and in parallel. A vehicle on which the battery pack according to claim 10 is mounted. The method of claim 13,
And a mechanism for converting kinetic energy of the vehicle into regenerative energy.

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